CQG: Cosmology from Group Field Theory Condensates

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In the first part of my talk, I will review the idea that a macroscopic universe like our own can be described as a condensate of loop quantum gravity spin network vertices in group field theory (GFT). Kinematics and dynamics of the Universe emerge from the hydrodynamic continuum approximation to the fundamental GFT: cosmology is the "hydrodynamics of quantum gravity." I will motivate the idea and show its realization in GFT: the hydrodynamic approximation connects the abstract group-theoretic and combinatorial language of GFT and LQG to the spacetime physics of cosmology. Specifically, I will show that GFT condensates can give an understanding of various features of LQC effective dynamics, while also suggesting possible phenomenology beyond LQC. In the second part, I will discuss recent results that show how quantum fluctuations in a GFT condensate can be responsible for cosmological inhomogeneities, somewhat similar to what happens in inflation but in a quantum field theory for both gravity and matter.